This invention relates to a pushbutton tuner, and more particularly to a pushbutton tuner in which pushbuttons and pushbutton slides are enabled to return positively and smoothly to their original positions without possibly entangling with other members in a tuner housing.
In the operation of pushbutton selectors for selection of radio stations, it is usual to disconnect a mechanism for a manual dial selector from a tuning mechanism by actuating a clutch releasing mechanism by any of pushbuttons pressed inwardly to release a clutch. Stated illustratively, the inner end of the button slide, when pressed inwardly, engages a cam formed in the clutch releasing mechanism to shift laterally the latter to one side to release the clutch for the selection of radio station as mentioned above. In this connection, it is to be noted that the clutch mechanism has a resilient member to urge the clutch releasing means expelled in one direction, in the opposite direction, for restoration of the clutch to its usual position. Accordingly, the button slide which is pressed inwardly to its retreated position is subjected to a lateral force for restoring the clutch to its original state. Though the button slide is provided with a spring for urging the button slide to its original projected position, the action of the spring is liable to be prevented by said lateral force from restoring the clutch to its original position and the button slide can be caught or locked by the cam of the clutch releasing means or at least prevented from smoothly returning to its original position. Thus, in case the button slide is pressed strongly to its innermost position, the button slide often remains in the pressed retreated position while being prevented from returning to its original position by its entanglement with the cam or other member of the housing.
The inventors of the present invention have considered the possibility of increasing the force of the button slide restoring spring. However, this is difficult or disadvantageous in view of the space problem occasioned by the necessary enlargement of the spring. Furthermore, even if the larger spring is employed, it causes another problem where the larger and stronger spring would hinder the easy smooth depression of the button slide. Furthermore, such a strong spring could make the button slide impact against the housing due to its strong force when the button slide is released, causing loosening of the connection of the pushbutton to the button slide and possible disengagement of the pushbutton from the button slide. This invention provides a solution to these problems with a means which is simple and reliable. The present invention is applicable both to single band and multi-band pushbutton tuner.